This invention relates to round balers that include a bale wrapping apparatus for wrapping a harvested crop material with a wrapping material, such as a net or twine, to produce geometrically-shaped bales of the harvested crop material for convenient transport and storage. More particularly, the present invention relates to a round baler with bale wrapping apparatus, wherein the round baler also includes an adjustable force wrapping material brake mechanism which compensates for the increase in the force required to pull wrapping material off of a material dispenser roll as the diameter of the material roll decreases. In particular, the force applied by the wrapping material brake mechanism decreases as the diameter of the wrapping material roll decreases, all to counteract the increased force required to pull material off of the roll as the roll diameter decreases, thereby maintaining relatively constant, the force required to dispense wrapping material throughout the dispensing of the dispensing roll. In a preferred embodiment, the operator can be made aware of the impending need to provide more wrapping material for the bale wrapping apparatus.
Balers often use netting, twine, plastic films, or other wrapping materials to wrap, and thereby confine and protect bales of forage immediately after bale formation while the bales are still within the baler. In particular, conventional balers typically incorporate wrapping material dispensers comprising a dispenser roll, which must be unwound from the roll before it is fed onto the newly formed bales. Thus, the provision of wrapping material is frequently achieved by unwinding such materials from pre-wrapped rolls mounted within the baler itself. Used as such, material on a pre-wrapped roll is drawn off of the roll in a constant stream and likewise fed into an automated wrapping assembly to be wrapped around the exterior portion of the bale. This drawing requires a pulling force to unwind the material.
One important aspect of this process is to ensure a tight and even supply of material by applying an opposing drag force to the dispenser roll as the constant stream of material is unwound. This provides a constant tension in the material that prevents bunching, recoil, entanglement, or overlap of the wrapping material.
Another important aspect of this process is the consistency of the wrapping from bale to bale, in terms of the rate of supply of, and thus the amount of, wrapping material used. This consistency is determined in part by the varying amount of force required to unwind the dispenser roll as the roll becomes smaller, in order to assure that a constant amount of material is dispensed. A newer roll, which is nearly full of material, has a wide diameter and as a result requires less force to unwind than an older roll, which is nearly empty. This force gradually decreases from bale to bale over the dispensing lifetime of each wrapping material roll. Thus, as wrapping material is depleted and the diameter of each roll decreases, the force required for unwinding the same amount of material at the same rate decreases. This change in required pulling force in turn, tends to promote inconsistent wrapping, from bale to bale, over the course of each dispenser roll""s lifetime. Therefore, a braking system a braking system is required to regulate or counteracts this tendency towards inconsistent bale wrapping.
U.S. Pat. No. 6,164,050 (xe2x80x9cthe ""050 patentxe2x80x9d) teaches such a dispenser roll braking system that varies the force by which the brake shoe is loaded against a friction disk connected to a dispenser roll in accordance with the actual amount of wrapping material remaining on the dispenser roll as determined by the diameter of the dispenser roll. As can be seen from FIG. 4, however, the ""050 patent teaches the use of a two-spring system, which biases the brake biasing arm 124 both vertically (131) and horizontally (126). In particular, the vertically biasing assembly includes a rod 129 pivotally attached to the upper end of the brake biasing arm 124. This rod 129 is used with a compression spring 131 mounted over the rod 129 to exert a force on the upper end of the brake biasing arm 124. It has been found however, that despite such teaching, a vertically biasing spring is unnecessarily complex and is therefore more likely to malfunction because it incorporates multiple spring assemblies.
Similarly problematic is the two-piece braking assembly comprising a load arm 119 and drag lever 117 both taught by the ""050 patent. Such a system is unnecessarily complicated and is prone to malfunction because it requires multiple parts.
The ""050 patent also requires that the stream of dispensed material be drawn from the bottom of the dispenser supply roll 88 and around idler roll 89 before it is fed into the bale forming chamber 16. This design requires the use of extra space that could other wise be used to house other electrical or mechanical assemblies and/or components. Thus, the ""050 patent""s requirement of additional assemblies and parts is unnecessarily complicated and bulky for its use within the confines of its baler housing.
Hence there exists a need for an improved adjustable brake mechanism and material dispensing assembly for varying the force by which a brake drags a dispenser roll in accordance with the actual amount of wrapping material remaining on the dispenser roll as determined by the diameter of the dispenser roll. In particular, there is a need for a brake mechanism and material dispensing assembly that uses fewer parts to minimize the chance of malfunction, and is more compact to allow for the placement of other not directly related components and assemblies.
Accordingly, an object of the present invention is to overcome the limitations of the prior art balers having adjustable brake mechanisms and material dispensing assemblies that use excessive parts, which heightens the chance of mechanical malfunction.
Another object of the present invention is to provide a baler having an adjustable brake mechanism that is more compact to allow for the placement of other not directly related components and assemblies.
In accordance with the above objects and other objects, which will be readily apparent to one having skill in the art, the present invention an adjustable force wrapping material brake mechanism and dispenser assembly for an agricultural baler. The assembly includes a wrapping material dispenser roll mount rotatably supporting a wrapping material dispenser roll and having a first longitudinal axis. A rotatable shaft is provided having a first end, a second end, and a second longitudinal axis substantially parallel to the first longitudinal axis. A brake biasing arm is provided having a first end fixedly connected to the first end of the rotatable shaft. A tension arm is provided having a first end fixedly connected to the second end of the shaft, and a second end bearing a counter roller disposed to roll on a surface of the material dispenser roll rotatably supported on the wrapping material dispenser roll mount. The tension arm has a first position corresponding to a substantially full wrapping material roll, and a second position corresponding to a substantially empty wrapping material roll. A brake drum is disposed to roll with the wrapping material dispenser roll. A pivotable monolithic brake lever arm is provided with a brake pad connected to one end. The brake lever arm is pivotable towards the brake drum causing the brake pad to contact the drum and thereby brake the dispenser roll. A tension spring connects the second end of the brake biasing arm and the other end of the brake lever arm to bias the brake pad to contact the brake drum with a biasing force, and thereby braking the dispenser roll. According to the invention, as wrapping material is dispensed and the counter roller moves from the first position to the second position, the tension arm rotates about the second longitudinal axis, thereby rotating the brake biasing arm about the second longitudinal axis to reduce the biasing force of the spring.
According to one preferred embodiment of the invention, the dispenser roll has a top and the material is fed from the top.
According to a further embodiment, the tension spring is the only spring biasing the brake biasing arm.
According to yet another embodiment of the invention, the brake mechanism further comprises a low wrapping material indication switch for providing an indication signal when the tension arm is in a position at or approaching the second position.
According to a still further embodiment of the invention, said wrapping material is netting, twine, or plastic film.
According to yet another embodiment of the invention, the counter roller extends from a position past a width of the wrapping material dispenser roll, and the wrapping material passes the tension arm over the top of the dispenser roll.
According to a still further embodiment of the invention, the assembly further comprises an actuator assembly for delivering wrapping material to a bale and movable from a first retracted position to a second extended position delivering wrapping material to the bale, wherein, when the actuator assembly is in the second position, the pivotable, monolithic brake lever arm is pivoted so that the brake pad does not contact the brake drum.